Stambaugh et al U.S. Pat. No. 4,093,125 discuss prior art methods of impregnating coal with a catalyst by (a) physical admixing of catalyst to coal or (b) soaking the coal in an aqueous solution of catalyst at room temperature and then drying the slurry. Stambaugh et al discloses a method of treating fine particles of solid carbonaceous fuel of a coal or coke type that comprises mixing the fuel particles with a liquid aqueous solution comprising essentially (a) sodium, potassium or lithium hydroxide together with (b) calcium, magnesium or barium hydroxide or carbonate.
Lancet in U.S. Pat. No. 4,248,605 discloses a method of gasifying the bottoms fraction from a coal liquefaction process by mixing the bottoms fraction with at least one finely divided calcium compound selected from the group consisting of calcium oxide, calcium carbonate and calcium hydroxide with the calcium compound being of a size consist no larger than about minus 200 Tyler mesh and present in an amount sufficient to produce agglomerate particles upon mixing with the bottoms fraction and thereafter gasifying the resulting agglomerate particles by reacting the agglomerate particles with steam in a fluidized bed.